This invention relates to an improved process and apparatus for control of corner shape in continuous or semicontinuous electromagnetic casting of desired shapes, such as for example, sheet or rectangular ingots of metals and alloys. The basic electromagnetic casting process has been known and used for many years for continuously or semicontinuously casting metals and alloys.
One of the problems which has been presented by electromagnetic casting of sheet or rectangular ingots has been the existence of high radius of curvature corners thereon. Rounding off of corners in electromagnetic cast sheet ingots is a result of higher electromagnetic pressure at a given distance from the inductor near the ingot corners, where two proximate faces of the inductor generate a larger field. This is in contrast to lower electromagnetic pressure at the same distance from the inductor on the broad face of the ingot remote from the corner, where only one inductor face acts.
There is a need to form small radius of curvature corners on sheet ingots so that during rolling cross-sectional changes at the edges of the ingot are minimized. Larger radius of curvature corners accentuate tensile stress at the ingot edges during rolling which causes edge cracking and loss of material. Thus, by reducing the radius of curvature of the ingot at the corners there is a maximizing in the production of useful material.
It has been found in accordance with the present invention that rounding off of corners in electromagnetic casting can be made less severe or of smaller radius by contouring the coolant application rate or elevation (or both) so that the rate and/or elevation is a minimum at the corners of the ingot.